A high level of comfort can be achieved at warmer temperatures, especially when occupants are provided with personal fans.

Credit: Graph adapted from Schiavon S, Yang B, Donner Y, Chang VW-C, Nazaroff WW By the year 2050, much of the world’s population will live in tropical climates, according to Stefano Schiavon, Assistant Professor at UC–Berkeley—and the temperature setpoint on their air conditioning units will have a big impact on energy usage. Luckily, a study conducted by Schiavon and several other researchers suggests that thermostat setpoints could be raised in warm, humid climates and actually improve occupant comfort, health, and productivity.

The research was informed by previous findings that occupants in office buildings in Singapore prefer warmer indoor temperatures and cite overcooling as the main cause for discomfort. A previous study has shown, in turn, that the overcooling commonly experienced in large commercial buildings often results from the need to provide adequate dehumidification in oversized HVAC systems.

The new study found that thermal comfort, perceived air quality, and symptoms of sick building syndrome were reported to be equal or improved at setpoints three and six degrees warmer than the common setpoint of 73.4°F (23°C). The increased temperature also helped occupants think better, increasing their productivity.

The researchers used four tests to measure how the indoor climate affected cognitive performance. The tests were administered through the cognitive testing platform Quantified Mind and included exercises to evaluate processing speed and motor function, as well as executive functions like inhibition (the ability to suppress a learned response) and context switching (the ability to switch attention between different tasks).

The researchers recorded the best cognitive performance at 78°F (26°C). At 84°F (29°C), the negative impact the warmer temperature has on cognitive performance was partially mitigated by supplying individual occupants with controllable fans. The lowest cognitive performance was recorded at 23°C (73.4°F), which happens to be the typical indoor temperature setpoint in Singapore.

These findings are significant considering that roughly 50% of the total electricity used in Singapore is used to cool commercial and residential buildings for occupant comfort. As global temperatures rise along with global population density and wealth, the demand for air conditioning in tropical regions of the world is expected to intensify.